For us to understand how the brain is impacted by mental illness, it is useful to appreciate how the brain functions normally. Every second, there are many thousands of chemical reactions occurring in the brain, controlling everything we do, both conscious and unconscious. This is what drives our thoughts and behaviours. Information is transmitted via neurons (cells) in the brain, which ‘talk’ to each other via the synaptic spaces between them. Learning is what builds these synaptic connections between neurons, and the more connections there are, the more ‘talking’ occurs between the neurons. Communication occurs when one neuron releases a chemical (known as a neurotransmitter) that the next neuron absorbs. It is thought that mental illness can be caused by problems with this communication between neurons, often influenced by the levels of neurotransmitters present to transmit these messages.
Low levels of neurochemicals in the brain impact on the effectiveness with which the neurons are able to communicate, and the number of synapses that can be built. This will hugely affect our cognition, since these processes are driven by neurons communicating with each other.
You may have heard of the expression ‘cells that wire together, fire together’ (a neuropsychologist called Donald Hebb first used this expression in 1949).
It explains how the neural pathways in the brain are formed through repetition and learning. The more we learn, the stronger and more effective these connections become. If these connections are compromised, how we think and learn will be affected.
Cognitive processes that are impacted by mental illness may include:
- Paying attention
- Clear rational thought
- Remembering and recalling information
- Processing information quickly
- Responding to information quickly
- Thinking critically
- Problem solving
- Categorizing and organizing information
- Making judgements and decisions
In summary, due to abnormal levels of neurochemicals in the brain, mental illness can influence how we think, perceive, understand, remember and respond. These cognitive processes occur due to a complex interaction of many factors in the brain, so it is no wonder that slight fluctuations in the chemistry and function of the brain can have such an impact.